1. Field of the Invention
This invention relates to a process for simultaneously producing methacrylonitrile and butadiene by simultaneously effecting ammoxidation and oxidation of mixed butenes containing as the substantial reactant isobutene and n-butenes in vapor phase.
Description of the Prior Art
Heretofore, efficient simultaneous production of methacrylonitrile and butadiene from mixed butenes containing isobutene and n-butenes by simultaneously effecting ammoxidation and oxidation in vapor phase using one and the same catalyst under common reaction conditions has been considered to be difficult due to difference in reactivity between isobutene and n-butenes.
A number of processes have recently been proposed for the production of methacrylonitrile from olefins by vapor-phase ammoxidation as well as for the production of butadiene from olefins by vapor phase catalytic oxidation. However, all of these processes involve separative use of isobutene or n-butenes alone, and there has scarcely been proposed the process for simultaneously producing methacrylonitrile and butadiene by vapor-phase oxidation of mixed butenes. Isobutene and n-butene are separated and purified usually from the B--B fraction (fraction containing a mixture of butanes, butenes and butadiene, namely C.sub.4 fraction) formed on cracking a petroleum fraction (for example, naphtha or kerosene, or crude oil) or the B--B fraction by-produced in purification of petroleum, and isobutene, 1-butene, cis-2-butene, trans-2-butene, trans-2-butene and butanes are quite similar in chemical and physical properties. Accordingly, separation and purification to isolate isobutene or n-butenes with a high purity are not easy and besides are expensive.